Kate and Gerry McCann yesterday issued a desperate plea for information about a bogus charity collector whose gang are feared to have snatched Madeleine.

Their spokesman Clarence Mitchell released sketches of the sinister-looking suspect and said: "We believe this man could be linked to Madeleine's disappearance. Who is he? Where is he?

"If he is innocent we want him to come forward for his own sake so he can be ruled out."

And Gerry McCann said last night: "We appeal to anyone who knows him or may have seen him to contact our investigators."

The McCanns' private detectives believe the dark-skinned stranger is part of a paedophile gang who had been operating near the Ocean Club in Praia da Luz for at least a fortnight before Madeleine vanished on May 3.

British witness Gail Cooper, 50, first noticed him wandering along the beach - then recognised him a couple of hours later when he knocked on her apartment door claiming he was collecting money for a non-existent orphanage.

Gail, staying with her family in a flat 600 yards from the McCanns' apartment, sent him away but noticed him taking an interest in her eight-year-old granddaughter.

Sketches are being prepared of at least one other gang member who knocked on doors in the resort peddling the same story.

British tourist Paul Gordon, 34, who in April was staying in the apartment later used by the McCanns, answered the door to a different bogus collector.

And a 12-year-old Portuguese girl was also pestered by a caller.

The sketches were produced after The Mirror passed details of Gail's sighting on to the McCanns. She contacted us after reading of Paul's encounter. They have been shown to key witness Jane Tanner who is convinced it is the same man she saw carrying a child from the McCann flat.

Gerry said: "The man has many similarities to the description given by Jane Tanner. She feels he has a strong resemblance to the man she saw carrying the child away. He may have key information that will help us to locate Madeleine."

A McCann family source said: "It's significant. This is the first time we have been able to produce a detailed picture of someone who could have taken Madeleine.

"Our agents have been speaking to a witness who has told us about another man seen around the area. We're doing all we can to get a similar image of him."

The McCanns' investigators suspect the gang concocted the orphanage story to enable them to prowl for potential victims.

The source said: "If these men were working together the charity story could have been an excuse to monitor the movements of people before selecting a child to abduct."

The man in the sketches is 38 to 45 with olive skin, long lank hair and a handlebar moustache.